Current aerodynamic exterior rearview mirror assemblies for vehicles comprise a mirror supported by a bracket that is mounted on a shell housing. This construction has led to several problems, the primary one being vibration caused by the door panel of the vehicle which is transmitted to the shell housing and, in turn, the rearview mirror. This vibration causes image distortion when viewed by the operator of the vehicle. Another problem is the quality of the manufacture of the mirror shell housing, which stems from the shrinkage caused by the mounting bosses molded for the purpose of holding mounting brackets, motor components and manual actuating mechanisms. Another problem specific to electrically operated rearview mirror assemblies, is that the mirror shell housing may amplify the noise generated by the electric motor mechanism.
Among the objectives of the present invention are to provide a rearview mirror assembly which minimizes the vibration from the door panel; which minimizes noise amplification within the mirror shell housing; which utilizes plastic compositions to dampen vibration from the door system; wherein the mirror has a natural frequency higher than the natural frequency of the door panel; and which is to provide relatively simple and economical design, manufacture and assembly.
In accordance with the invention, an exterior rearview mirror assembly that is attached to the side wall of the door of a vehicle having a mirror shell housing mounted on the side wall and a mirror mounting bracket mounted in cantilever fashion on the side wall. The mirror mounting bracket preferably comprises a body having a triangular shape cross section with first and second side walls forming a cavity, the cavity opening to a third side. A plurality of truss walls are interposed between the first and second side walls of the mirror mounting bracket and are constructed and arranged to increase the damping characteristics and natural frequency of the mirror mounting bracket.
A plurality of integral bosses are provided on one end of the mirror mounting bracket and receive bracket screws that hold the mounting bracket to the door of the vehicle. A plurality of integral sleeves project from the third side of the mounting bracket and a mirror mounting mechanism is mounted thereon.
The mirror mounting bracket is preferably fabricated from a glass and mineral filled nylon fiber material and preferably the fibers of the nylon material are oriented longitudinally of the mirror mounting bracket.
An important advantage of this present invention is that by isolating the mirror mounting bracket from the mirror shell housing and designing the mirror mounting bracket to dampen the vibration from the door, image distortion problems are eliminated and noise is reduced within the mirror shell housing.
Other objects and features of the invention will become apparent in the following description and claims in which the invention is described together with the details to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.